Background: Obese patients have a propensity to desaturate during induction of general anesthesia secondary to their reduced functional residual capacity and increased oxygen consumption. Apneic oxygenation can provide supplemental oxygen to the alveoli, even in the absence of ventilation, during attempts to secure the airway. In this study, we hypothesized that oxygen administration through a nasopharyngeal airway and standard nasal cannula during a simulated prolonged laryngoscopy would significantly prolong the safe apneic duration in obese patients.
Methods: One hundred thirty-five obese patients undergoing non-emergent surgery requiring general anesthesia were randomized to either the control group or to receive apneic oxygenation with air versus oxygen. All patients underwent a standard intravenous induction. For patients randomized to receive apneic oxygenation, a nasopharyngeal airway and standard nasal cannula were inserted. A simulated prolonged laryngoscopy was performed to determine the duration of the safe apneic period, defined as the beginning of laryngoscopy until the peripheral oxygen saturation (SpO2) reached 95%.
Results: The oxygen group had a median safe apneic duration that was 103 s longer than the control group. The lowest mean SpO2 value during the induction period was 3.8% higher in the oxygen group compared to the control group. Following intubation, patients in the oxygen group had a mean end tidal carbon dioxide (ETCO2) level that was 3.0 mmHg higher than patients in the control group.
Conclusions: In obese patients, oxygen insufflation at 15 L/min through a nasopharyngeal airway and standard nasal cannula can significantly increase the safe apneic duration during induction of anesthesia.
Keywords: Airway management; Apneic oxygenation; Difficult intubation; Laryngoscopy; Obesity.